Most motorcycle helmets and some bicycle helmets have a face shield to protect a rider's eyes from debris, bugs, and wind. The rider can typically raise the shield to a fully open position to increase helmet ventilation or to defog the interior surface of the shield. Unfortunately, the typical helmet does not allow the rider to partially open the shield without the oncoming wind blowing the shield into a different position.
U.S. Pat. No. 4,612,675 teaches a helmet with a shield that can be raised and locked into a single intermediate position. To release the shield from the intermediate position, the rider must disengage a control mechanism on the side of the helmet. There are at least two major problems with this type of helmet. First, the process of disengaging the control mechanism is both awkward and dangerous when done while riding. Second, with only one intermediate shield position, the rider cannot adjust the volume of air flowing into the helmet. At high speeds, the rider may only need to open the shield a small amount in order to adequately defog the shield and increase helmet ventilation. On the other hand, at lower speeds the rider may need to open the shield almost to the fully open position to get adequate air flow.
Separate problems arise with the shield itself, which is typically mounted onto a frame that is attached to the helmet. First, the dynamic, high-stress environment of motorcycle and bicycle riding can cause the shield to vibrate free from or to be jolted off of the shield frame. Second, although the shield must be occasionally replaced because of debris damage, replacing a frame-mounted shield is difficult and time consuming. An additional problem is that the shield frame increases the overall weight of the helmet, thereby increasing the load that the rider's head must bear.
A further problem arises with the light-filtering qualities of the typical face shield. In the early days of motorcycles, a rider would wear goggles in order to protect his or her eyes from wind, insects, and debris. However, goggles did nothing to protect the rider's face from extended exposure to sunlight. Many riders suffered sun burn on their cheeks, nose, and forehead, and ran the risk of contracting skin cancer.
As motorcycle riding became more advanced, riders began wearing helmets having a face shield. Although such face shields protected the rider from wind, insects, and debris, the shields did not protect the rider's face from the sunlight. Overexposure to sunlight has been a particular problem for touring riders, who can be exposed to the sun for eight or more hours per day. Some riders have worn sunglasses underneath their helmet in order to protect their eyes, but the glasses have tended to fog-up and to slip around on the rider's face in the warm, humid atmosphere inside the helmet. Furthermore, the sunglasses have not protected the rider's entire face from the sun. Likewise, some riders have experimented with wearing ski goggles underneath their helmets. However, ski goggles become quite uncomfortable and also fail to protect a rider's entire face.
In view of the positioning problems of the typical helmet shield, the problems associated with frame-mounted helmet shields, and the light-filtering problems with known shields, the present invention addresses itself to a one-piece helmet face shield with a bi-directional ratchet positioning system and a face shield that filters ultraviolet rays.